Angle Finder Protractor

ABSTRACT

An angle indicating instrument which, used in conjunction with a sliding T-Bevel, can indicate to users what miter saw setting to use when cutting two pieces of material for a miter joint, or for cutting one piece of material requiring a miter cut.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/261,851, filed Dec. 1, 2015, entitled “Angle Finder Protractor”,which is incorporated by reference herein in its entirety.

BACKGROUND

Field of the Invention

The present invention is directed to an instrument and method fordetermining and displaying the appropriate angle setting for a powermiter saw for cutting miter ends and miter joints.

Most power miter saws sold today are fitted with miter saw gauges whichdisplay the angle of the miter cut. However, the markings andgraduations on such miter saw gauges are often counterintuitive and veryconfusing for less experienced users and even for professional users.Finish carpenters, in particular, when installing crown molding or trimin a room, must make numerous double mitered joints where the walls meetat an angle. The miter angle is half of the angle of the required turn.For example, if molding must make a right angle, i.e., a 90° turn, eachof the adjacent pieces is cut to a 45° angle where they are to bejoined.

In practice, walls often meet at angles which are not perfectly 90°. Forthese situations, a popular current method for calculating the miter sawsetting for the double miter cut involves the following steps:

a) Transferring (“picking up”) the actual angle between the twoadjoining walls to a Sliding T-Bevel;b) Laying the Sliding T-Bevel on top of a protractor, so as to measurethe actual angle;c) Subtracting the measured angle from 180°, then dividing thesubtraction result by 2, to obtain the setting needed for the miter sawangle gauge.

For single miter cuts (such as the angled end cut required for the stairspindles), the calculation would be:

a) From the acute position of the spindle: miter saw setting=90° minusthe measured angle;b) From the obtuse position of the spindle: miter saw setting=themeasured angle minus 90°.

The counterintuitive calculations described above are necessary becausethe value of the measured angle is different from the miter anglesetting to be used on a miter saw. These calculations are challenging toeven experienced craftsmen, often pushing users to resort to a processof trial and error in order to obtain the proper angle setting neededfor the miter saw. Specialized digital angle measuring and calculatingdevices (to facilitate setting the proper miter saw angle for such mitercuts) are commercially available, however they are quite expensive.

There is an unmet need in the market for a simple and inexpensive devicethat could translate the actual angle between two adjoining walls (aspicked up by a Sliding T-Bevel) directly into the proper angle settingfor a power miter saw, without the need for calculations. It would alsobe very desirable for such a device to be useable for single miter cutsas well as for double miter joint cuts.

Related Art

U.S. Pat. No. 4,394,801 to Thibodeaux discloses a construction tool thatis used to measure the relative angle between two lines or surfaces orbetween horizontal or vertical and such a line or surface. It alsoindicates roof pitch on a separate scale. Bubble type levels areincluded to orient the construction tool with respect to horizontal orvertical.

U.S. Pat. No. 4,562,649 to Ciavarella discloses an adjustablecarpenter's square for use determining the relative angle between twolines or surfaces. The absolute angle between the two lines isindicated, and is viewed through opening 31.

U.S. Pat. No. 4,745,689 to Hiltz discloses a measuring and layout toolthat has a plurality of levels therein and indicates the relative anglebetween two lines or surfaces.

U.S. Pat. No. 4,144,650 to Rawlings et al. discloses a multifunctionlevel that again shows the relative angle between two lines or surfaces.This level can be locked at a particular angle, if desired, with thelocking mechanism accessible from either side of the level, thus makingit easier to use.

U.S. Pat. No. 2,735,185 to Naphtal discloses a protractor that is usedto measure angles between two lines or surfaces. The angle of theprotractor is lockable thereby also allowing it to be usable to recreatethe angle in order to draw it accurately on paper or wherever. The angleis viewed through a magnifying bubble located above the scale.

U.S. Pat. No. 1,655,887 to Bailey discloses a protractor that may beused to very accurately measure angles between two lines or surfaces orto very accurately measure very small angles, and works in the followingmanner. As the blades 5 and 6 are moved angularly with respect to oneanother, gear teeth 9, which are part of ring 7 that is in turn attachedto blade 5, cause the free turning gear 11 to rotate. Gear 11 is part ofthe plate 10 that is attached to blade 6. Gear 11 meshes with gear 12and causes it to turn. Rigidly attached to gear 12 is plate 13. Plate 13is caused to be angularly displaced at a much greater rate then the twoblades 5 and 6 are separated at. This is because the ratio of the gearteeth on gears 9, 11 and 12 cause gear 12 to move at an angular speedthat is greater than gear 9.

U.S. Pat. No. 1,585,563 to Schlattau discloses a combination measuringinstrument that measures the relative angle between two lines orsurfaces, and provides a linear measuring scale, a means for measuringthe outside diameter of an object, and also a scale that is used tomeasure the diameter of a bolt or a piece of wire. The scale formeasuring a bolt or a piece of wire is an enlarged scale.

U.S. Pat. No. 1,550,755 to Steinle discloses an angulometer that is usedto measure the relative angle between two lines or surfaces, including amagnifying lens to allow a very fine angular scale to be read easily.

U.S. Pat. No. 4,733,477 to Fincham et al. discloses a chalk line framingsquare that provides a device that is designed to aid in placing rightangle intersecting chalk lines upon a floor so that tiles can beproperly installed on the floor. It includes two arms that pivot withrespect to one another and an angular scale that indicates the anglebetween the two arms.

SUMMARY OF THE INVENTION

The present invention responds to this unmet need in the market byintroducing a simple and inexpensive protractor device, adapted to workwith any standard Sliding T-Bevel so as to directly provide to users theproper miter saw setting for double miter joint cuts and for singlemiter cuts.

The protractor device of this invention is designed to work withstandard size Sliding T-Bevels to enable the users to read directly theproper miter saw setting needed for the particular desired miter cut.One face of the protractor has specific markings indicating the settingfor double miter joint cuts, while the reverse face of the protractorhas specific markings indicating the setting for single miter cuts. Afunctional shape feature on the bottom part of the protractor ensuresthat the Sliding T-Bevel is always placed in the correct orientation onthe protractor's face.

The invention provided herein gives a person working with wall trim(such as chair rail, cove molding, crown molding, base board and otherjoinery) as well as with non-decorative trim installations such as handrail, spindles, flooring, aerospace applications and other situationswhere angles have to be taken from a surface or an edge and measured fora subsequent operation, a scale that reads directly the miter anglesetting for use on a miter saw having an angle scale incorporatedthereon.

According to a preferred embodiment of this invention, a protractor isprovided that has a half-circle disk with angle scale measurementsscribed thereon. The protractor also has a tab jutting out from thebottom edge, which tab serves to ensure that a Sliding T-Bevel is alwaysplaced properly on the face of the protractor so as to read the propersetting needed for the miter saw. To further guide the user in properplacement of the Sliding T-Bevel relative to the protractor,instructional wording or pictograms may be provided on the face or atcertain points along the bottom edge of the protractor, to indicate theproper place where the Sliding T-Bevel should engage the protractor (forexample, inscriptions such as “place the Sliding T-Bevel here” or a tinypicture showing a Sliding T-Bevel correctly positioned on theprotractor).

Alternative embodiments of this invention may have the twoquarter-circle portions (of the overall half-circle disk) transposedslightly apart, to allow a raised member to be positioned in the centralvertical surface gap thus created, on one or both faces of theprotractor. The role of such raised member(s) is to further guide theproper positioning of the T-Bevel relative to the protractor, ensuringan accurate angle reading.

According to a preferred embodiment of this invention the protractor hastwo faces, which can be accessed simply by flipping over the protractor.One face of the protractor has the miter saw angle settings for singlemiter cuts, while the other face of the protractor has the miter sawangle settings for the cut needed for double miter joints. Inalternative embodiments of this invention, single-faced protractors(with one scale for either single miter cuts or for double miter jointcuts) can be sold individually, or in sets of two, or combined on oneface.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are believed to be characteristic of thepresent invention, as to its structure, functionality, use and method ofoperation, together with further objectives and advantages thereof, willbe better understood from the following drawings in which a presentlypreferred embodiment of the invention will now be illustrated by way ofexample. It is expressly understood, however, that the followingdrawings are for the purpose of illustration and description only, andare not intended as a definition of the limits of the invention. In theaccompanying drawings:

FIG. 1 is a picture of a standard PRIOR ART Sliding T-Bevel of the typethat is to be used with the present invention;

FIG. 2 is a front view of a protractor according to this invention;

FIG. 3 is a rear view of a protractor according to this invention;

FIG. 4a is a front view of a protractor according to this invention,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “acute angle”, whereby the user can directly read therequired miter saw setting for the single miter cut (in the specificexample in FIG. 4a , this setting is 43°);

FIG. 4b is a front view of a protractor according to this invention,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “obtuse angle”, whereby the user can directly read therequired miter saw setting for the single miter cut (in the specificexample in FIG. 4b , this setting is also 43°).

FIG. 5a is a front view of a protractor according to this invention; itis the same as FIG. 4a above, but with the blade of the Sliding T-Beveldepicted semi-transparently, so as to better show the portions of theprotractor underneath the Sliding T-Bevel;

FIG. 5b is a front view of a protractor according to this invention; itis the same as FIG. 4b above, but with the blade of the Sliding T-Beveldepicted semi-transparently, so as to better show the portions of theprotractor underneath the Sliding T-Bevel.

FIG. 6 is a rear view of a protractor according to this invention,depicted in functional engagement with the Sliding T-Bevel, whereby theuser can directly read the required miter saw setting for the doublemiter joint cut (in the specific example in FIG. 6, this setting is18°).

FIG. 7 is a rear view of a protractor according to this invention; it isthe same as FIG. 6 above, but with the blade of the Sliding T-Beveldepicted semi-transparently, so as to better show the portions of theprotractor underneath the blade of the Sliding T-Bevel.

FIG. 8 is a composite front, top and side view of a protractor accordingto an alternative embodiment of this invention, with a raised memberpositioned on each face, along the central vertical axis of theprotractor.

FIG. 9 is a composite front, top and side view of the obverse face ofthe same embodiment from FIG. 8 above.

FIG. 10 shows front views of both faces of a protractor according to afurther alternative embodiment of this invention, whereby the bottomedge of the protractor is flush and level with the horizontal linerunning from the leftmost to the rightmost angle mark on the protractordial.

FIG. 11 is a front view of the same embodiment from FIG. 8 above,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “obtuse angle”, whereby the user can directly read therequired miter saw setting for the single miter cut (in the specificexample in FIG. 11, this setting is 43°).

FIG. 12 is a front view of the same embodiment from FIG. 8 above,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “acute angle”, whereby the user can directly read therequired miter saw setting for the double miter cut (in the specificexample in FIG. 12, this setting is 57°).

FIG. 13 is a front view of the same embodiment from FIG. 8 above,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “obtuse angle”, whereby the user can directly read therequired miter saw setting for the double miter cut (in the specificexample in FIG. 13, this setting is 18°).

FIG. 14 is a front view of the same embodiment from FIG. 8 above,depicted in functional engagement with a Sliding T-Bevel which haspicked up an “acute angle”, whereby the user can directly read therequired miter saw setting for the single miter cut (in the specificexample in FIG. 14, this setting is 43°).

DESCRIPTION OF THE INVENTION

To clarify the terms used herein:

a) A single miter cut is just one angled cut to one workpiece. A singlemiter cut is made for one workpiece to fit to an angle. A cross-cut isan example of a single miter cut.b) A double miter joint is formed when two parts must join to form acorner; to achieve this, each of the two pieces must be miter cut to anequal miter angle.

Referring now to the invention in more detail, FIG. 1 illustrates atypical PRIOR ART Sliding T-Bevel of the type that is to be used withthe present invention. A Sliding T-Bevel of this type consists typicallyof a pivoting/sliding blade, a handle and a thumbnut which can betightened to lock the blade relative to the handle. A Sliding T-Bevel,as known in the prior art, is often used for transferring a measuredangle to the workpiece. If one needs to measure an angle between twophysical objects (e.g. two adjoining walls), one will place the SlidingT-Bevel along the sides of the angle (e.g. adjoining walls in a corner),making sure the sides of the Sliding T-Bevel are aligned to the sides ofthe corner. Subsequent tightening of the thumb nut will allow theSliding T-Bevel to retain the transferred angle even after removal fromthe corner.

FIG. 2 is a front view of a protractor according to this invention. Onthis face, the protractor has the miter saw angle settings for singlemiter cuts. The protractor consists of the half circle disc 1, withangle scale measurements scribed thereon, with the 0 (zero) setting atthe topmost vertical position and with settings of 90 (ninety) at bothextreme left and right horizontal ends; a horizontal line 4 runs betweenthese two horizontal ends. The bottom edge 5 of the protractor isparallel with the horizontal line 4.

A tab 2 is extending down from the bottom edge 5 of the protractor,which tab 2 serves to ensure that a Sliding T-Bevel is always placedproperly on the face of the protractor so as to read the proper sawsetting needed for the desired miter saw cut. The width of the tab 2 issmaller than the width of the bottom edge 5. FIGS. 4a, 4b, 5a and 5bshow how a Sliding T-Bevel is placed properly on the face of theprotractor to read the proper saw setting for the desired miter cut. Asshown in FIGS. 4a, 4b, 5a and 5b , the tab 2 makes it impossible for theSliding T-Bevel to engage the protractor in the wrong orientation.

Also seen in FIG. 2 is the origin 3, which is the point where thevertical and horizontal axes of the half circle disc intersect. Alsoseen in FIG. 2 is the inscription “SINGLE MITER” on this face, whichtells the user that this is the face of the protractor that must be usedto determine the saw setting needed for single miter cuts.

FIG. 3 is a rear view of a protractor according to this invention, whichshows the face opposite to the face shown in FIG. 2. On this face, theprotractor has the miter saw angle settings for the double miter jointcut. Accordingly, the graduations on this face are different from thoseshown in FIG. 2, namely a setting of 45 (forty five) at the topmostvertical position, and with a setting of 90 (ninety) at the lefthorizontal end, and with a setting of 0 (zero) at the right horizontalend.

As seen in FIG. 3, the tab 2 is extending down from the bottom edge 5 ofthe protractor (on the opposite side compared to FIG. 2, as a result ofthe protractor being flipped over). As shown in FIG. 6 and FIG. 7, thetab 2 makes it impossible for the Sliding T-Bevel to engage theprotractor in the wrong orientation.

Also seen in FIG. 3 is the inscription “DOUBLE MITER JOINT” on thisface, which tells the user that this is the face of the protractor thatmust be used to determine the saw setting needed for double miter jointcuts.

As seen in FIGS. 8 and 9, an alternative embodiment of this inventionhas the two quarter-circle dial portions of the protractor (of theoverall half-circle disk) transposed sideways slightly apart; as aresult of this transposition, there are now two origins, namely 3 a and3 b, with origin 3 a corresponding to the left quarter-circle portionand origin 3 b corresponding to the right quarter-circle portion. In thegap between the origins 3 a and 3 b, on both faces of the protractor, araised member 6 is rigidly positioned along the central vertical axis ofthe protractor, one such raised member 6 on each face of the protractor.

The raised member 6 does not extend below the horizontal line 4 on theprotractor. The raised member 6 intersects with the horizontal line 4 attwo points which correspond exactly with the two origins 3 a and 3 b. Asa result of this positioning, the raised member 6 offers (for possibleabutting engagement) two raised edges 6 a and 6 b, orientedperpendicularly to the plane of the protractor and corresponding exactlywith the two origins 3 a and 3 b. The functional result of suchstructure is that any other straight edge, if laid onto the protractor,parallel to the plane of the protractor and abutting against one of theraised edges 6 a or 6 b, will be perfectly and automatically alignedwith the origins 3 a or 3 b, reducing the need for an user to manuallyeffect such alignment.

For an accurate angle reading according to this embodiment, the usersimply positions the handle of the T-Bevel abutting (and flush with) thebottom edge 5 of the protractor, while bringing either edge of the bladeof the T-Bevel to rest against the raised edges 6 a or 6 b of the raisedmember 6; the proper saw setting can then be read where the same edge ofthe blade of the T-Bevel intersects the angle-graduated dial.

As seen in FIG. 10, a further alternative embodiment of this inventionis similar to the embodiment shown in FIGS. 2-7, with the modificationthat the bottom edge 5 of the protractor is aligned and flush with thehorizontal line 4. By contrast, in the embodiment shown in FIGS. 2-7,the bottom edge 5 of the protractor is parallel with the horizontal line4, but slightly offset from the horizontal line 4.

METHOD OF USE

To use this invention, a handyman would need first to determine whatkind of miter cut is needed (double miter joint cut, or single mitercut) and then choose the appropriate face of the protractor from whichto make the reading (either the face shown in FIG. 2 or the face shownin FIG. 3).

For a double miter joint cut, the user needs then to measure the angleat the corner between the two adjoining walls, by placing the SlidingT-Bevel along the adjoining walls in the corner, making sure the sidesof the Sliding T-Bevel are aligned to the sides of the corner.Subsequent tightening of the thumb nut will allow the Sliding T-Bevel toretain the transferred angle even after removal from the corner.

For a single miter cut, the user sets the angle of the Sliding T-Bevelto the existing angle and parallel with the material to be cut.

The next step involves the placement of the Sliding T-Bevel onto theappropriate face of the protractor from which to make the reading(either on the face marked “SINGLE MITER”, as shown in FIGS. 4a-4b andFIGS. 5a-5b , or on the face marked “DOUBLE MITER JOINT”, as shown inFIG. 6 and FIG. 7). For a proper angle setting reading on both faces,care must be taken to ensure that the edge of the blade of the SlidingT-Bevel must pass through (must be aligned with) the origin 3 marked onthe center of the protractor. The handle of the Sliding T-Bevel must bein abutting parallel alignment with the bottom edge of the protractor.The user can then read directly the miter saw angle setting on thesemicircular graduated scale.

In the example illustrated in FIGS. 4a, 4b, 5a and 5b , the user reads asetting of 43° for a single miter cut. The user will then adjust theangle of his power miter saw blade to point to a setting of 43° on themiter saw angle gauge (normally indexed around the edge of the miter sawtable), and will proceed to make the cut.

In the example illustrated in FIG. 6 and FIG. 7, the user reads asetting of 18° for a double miter joint cut. The user will then adjustthe angle of his power miter saw blade to point to a setting of 18° onthe miter saw angle gauge (normally indexed around the edge of the mitersaw table), and will proceed to cut each of the two pieces that willform the miter joint.

To use the embodiment of the invention depicted in FIGS. 8-9, the usersimply positions the handle of the T-Bevel abutting (and flush with) thebottom edge 5 of the protractor, while bringing either edge of the bladeof the T-Bevel to rest against the raised edge 6 a or 6 b of the raisedmember 6; the proper saw setting can then be read where the same edge ofthe blade of the T-Bevel intersects the angle-graduated dial. The roleof the raised member 6 is to ensure that the edge of the blade of theT-Bevel always passes through (is aligned with) the origins 3 a or 3 b;this is accomplished automatically and in a foolproof manner whenever anedge of the blade of the T-Bevel is brought to bear against the raisededges 6 a or 6 b of the raised member 6.

The embodiment of the invention depicted in FIG. 10 is used in the samemanner as the embodiments depicted in FIGS. 2-7, as described above.

As to their construction, the embodiments of this invention, as shown inFIGS. 2-10 and discussed above, may be made of any suitable material ofsufficient rigidity, strength and thickness, such as steel, stainlesssteel, aluminum, other metals and alloys, plastic, etc. Various sizes ofprotractors according to this invention can be manufactured, so as to beable to work with common sizes of Sliding T-Bevels. The raised dimensionof the raised member 6 should be of any thickness sufficient to permitstable engagement between the blade of a T-bevel and the raised edges 6a or 6 b of the raised member 6. The raised member 6 may be made unitarywith the protractor, or may be manufactured separately and fitted to theprotractor by any known permanent or temporary attaching means.

The present invention also includes any possible additional variants ofthe embodiment depicted in FIGS. 8-9, which may employ, aside from theraised member 6 described above, other known structural solutions toachieve the functionality of “centering means” for the engagementbetween a T-Bevel and the protractor according to this invention.Possible examples of such alternative “centering means” are (not anexhaustive list): i) a raised feature (pin) on the T-Bevel blade mayslidingly engage (mate with) a depressed feature (hole) in theprotractor (or vice-versa), positioned to effect alignment with origins3, or 3 a, or 3 b; ii) the raised member 6 may be reduced to one pin (orseveral pins) positioned to act as “centering means” on the origins 3,or 3 a, or 3 b; iii) the raised member 6 may be reduced to one narrowraised “thin blade”, effectively offering for engagement just one raisededge corresponding to origin 3.

The advantages of various embodiments of the present invention include,without limitation, being inexpensive to manufacture, easy to use, beingable to work with Sliding T-Bevels (and with other tools of the samefunctionality as Sliding T-Bevels) and being able to directly providethe proper saw setting needed for the desired miter saw cut.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. The inventionshould therefore not be limited by the above described embodiment,method and examples, but by all embodiments and methods within the scopeand spirit of the invention.

I claim:
 1. A protractor for assistance in determining miter saw anglesettings for miter cuts, said protractor comprising: a top edge; atleast one face with angle markings; a bottom edge and a tab adjacent tothe bottom edge and extending lower than said bottom edge.
 2. Theprotractor of claim 1, whereby the at least one face further comprises:a horizontal line, disposed near or on the bottom edge and parallel tothe bottom edge; at least one vertical axis, disposed perpendicularly onthe horizontal line; at least one origin defined as a point where thehorizontal line intersects with the at least one vertical axis.
 3. Theprotractor of claim 2, whereby the at least one face further comprisesat least one raised member having at least one raised edge, whereby theat least one raised edge is perpendicular to the at least one face andintersects said at least one face at a point which is the at least oneorigin.
 4. The protractor of claims 1-3, whereby the at least one facefurther comprises markings, pictograms and indicia for properidentification, positioning and use of the protractor in conjunctionwith a Sliding T-Bevel.
 5. The protractor of claims 1-4, whereby the atleast one face comprises one obverse face and one reverse face.
 6. Theprotractor of claim 5, whereby the obverse face has angle markingsadapted to read miter saw angle settings for single miter cuts, and thereverse face has angle markings adapted to read miter saw angle settingsfor double miter joints.
 7. A method for using the protractor of claims1-6 for determining miter saw angle settings for miter cuts, said methodcomprising the steps of: Transferring a target angle to a SlidingT-Bevel having a handle edge and a blade edge; Positioning said SlidingT-Bevel in a functional engagement with said protractor, whereby thehandle edge is in abutting engagement with the bottom edge and the bladeedge is aligned with the at least one origin; Reading a resultant mitersaw angle setting value according to a nearest alignment between theblade edge and the angle markings; Whereby said tab prevents the handleof the Sliding T-Bevel from engaging the bottom edge of the protractorin an improper orientation.
 8. The method of claim 7 whereby thealignment between the blade edge and the at least one origin isautomatically effected when the blade edge is in abutting engagementwith the at least one raised edge.
 9. A kit comprising the protractor ofclaims 1-6 and a customized Sliding T-Bevel having a handle edge and ablade, whereby: said protractor is further fitted with protractorcentering means; said customized Sliding T-Bevel is further fitted withT-bevel centering means; said protractor centering means are adapted toeffect a reversible interlocking engagement with said bevel centeringmeans; whereby said interlocking engagement automatically aligns theblade with the at least one origin; and whereby said protractorcentering means and T-bevel centering means are selected from the groupconsisting of (pin and hole; matching interlocking members; magneticcentering means; key and hole centering means; hook and loop centeringmeans; socket and ball centering means; snap centering means)
 10. Amethod for using the kit of claim 9 for determining miter saw anglesettings for miter cuts, said method comprising the steps of:Transferring a target angle to the customized Sliding T-Bevel;Positioning said Sliding T-Bevel in a functional engagement with saidprotractor, whereby the handle edge is in abutting engagement with thebottom edge and the protractor centering means are in a reversibleinterlocking engagement with said bevel centering means; Reading aresultant miter saw angle setting value according to a nearest alignmentbetween the blade and the angle markings.